1. Field of Invention
This invention relates to a case separating apparatus for separating a group of cases, e.g. comprising cases of containers made of synthetic resin, carrying cases of corrugated carton, or the like, wherein the cases are stacked in plural layers and arranged in rows.
2. Description of Related Art
As an example of a conventional cases separating apparatus for separating individual cases from a plurality of cases stacked in groups of cases layer by layer, there is an apparatus wherein a pallet mounting groups of cases arranged in plural rows is intermittently forwarded to an unloading position on a carrying conveyor, and groups of plural rows mounted on the pallet are moved row by row onto an elevating conveyor. When the elevating conveyor is vertically moved up and down by an air cylinder, the groups of the remaining upper layer stacked on the elevating conveyor,except the cases in the bottom layer, are held in an upright position by right and left support arms, while the cases of the bottom layer stacked on the elevating conveyor are separated and mounted on a distributing conveyor.
In this method, however, when the elevating conveyor is moved vertically up and down by the air cylinder, when separating each case of the bottom layer, after holding the cases stacked on the second layer from the bottom on the elevating conveyor by right and left support arms, the elevating conveyor mounting the cases of the bottom layer is vertically lowered to the descending position, and hence the cases mounted on the elevating conveyor are moved about due to the shock of descending and stopping, and noise is caused by the momentary contacting and departing action of the elevating conveyor with the cases.
When separating the cases in the second layer, since the elevating conveyor is vertically raised at once to the ascending position to lift the remaining case groups held by the right and left support arms swiftly by the elevating conveyor, the cases of the bottom layer held by the support arms and the elevating conveyor collide, and a large noise is caused by the impact of the collision. If the impact occurring at the time of the ascending and stopping and descending and stopping is large, the contents in the cases may be bruised or damaged, and the commercial value of the contents may be spoiled.
Besides, when cases containing a multiplicity of products are stacked in plural layers, the center of gravity of the case group is raised, and the stacking position of the case group becomes unstable, and hence when driving or stopping the carrying conveyor, the group of the final row stacked on the pallet may collapse, and unloading may not be done smoothly.
Since the pusher plate is moved reciprocally at a constant speed, the pusher plate may momentarily collide against each case group of one row stacked on the pallet, and a large noise is caused by the impact of mutual collision. If the impact of collision is significant, the commercial value of the products in the cases may be spoiled.
On the other hand, when the moving speed of the pusher is lowered, it takes a long time to move reciprocally, and it requires more time and labor in unloading the groups of one row, and the working efficiency is poor. When the moving speed of the pusher plate is increased, the groups of cases may tumble due to inertia when unloading, or it may be difficult to stop each group of cases of one row at a predetermined position.
Still more, when the stopping position of the cases mounted on the elevating conveyor is deviated or reinforcing ribs are projecting to both sides of the case, it may be difficult to stop the right and left case holding plates at both side edges of the case, or when separating vertically, the group of cases on the upper side may drop or tumble by gravity.